1. Field of the Invention
The invention relates to a testing device for a cam-driven fuel injection system, in particular a unit injector injection system or unit pump injection system.
2. Description of the Prior Art
In modern diesel engines, a fuel injection system injects the fuel at high pressure directly into the combustion chamber. There are various types of fuel injection systems used for this, for example unit injector injection systems or unit pump injection systems. Both fuel injection systems are actuated directly on the engine itself by means of a cam shaft. Via a lever, a cam on the cam shaft produces a stroke of a pump piston of the fuel injection system. This produces a very high pressure at a nozzle of the fuel injection system, which pushes a valve needle into an open position and as a result, fuel is injected into a combustion chamber of the engine. The injection quantity is adjusted by means of a solenoid valve, which controls the buildup of pressure in the fuel injection system.
The injection pressure and the injection quantity depend, among other things, on the shape of the cam and its stroke. Different fuel injection systems have different strokes and cam shapes. In some cases as well, identical fuel injection systems are actuated with an identical stroke in different types of engines with different cams.
Testing devices used for testing purposes and for the quality control of the above-described cam-driven fuel injection systems are known from the market. One such testing device has a cam-driven fuel injection system built into it. The piston of the fuel injection system is acted on by means of a cam shaft and a lever so as to simulate an operating situation. In the known testing device, the same cam is used for various types of fuel injection systems and all fuel injection systems are operated with the same stroke. In order to avoid damage, this stroke is relatively small. There is also a known testing device in which the cams of the cam shaft are replaceable. It is thus possible to associate each fuel injection system with a specific cam.